Styrene copolymers Butadiene-methylmethacrylate

Figure 1.2. Izod impact strength at room temperature as a function of diameter of elastomeric particles in methylmethacrylate-butadiene-styrene copolymer used for toughening polyvinylchloride resin [after Bertelo and Mori, 1994].

Predesigned particles of impact modifiers are based on core-shell technology. Core is involved in impact modification and shell improves adhesion between PVC and impact modifier particles.Three major combinations are used methacrylate-butadiene-styrene, MBS, which has a core made out of butadiene-styrene copolymers and shell made out of methylmethacrylate-styrene copolymer, acrylic impact modifiers, AIM, which have a core made out of acrylic and shell from polymethylmethacrylate, and silicone-acrylic have multilayer structures with silicone-acrylic in the core. MBS has excellent compatibility with PVC, similar to ABS, which is used as an impact modifier of PVC, as well. In both cases of ABS and MBS, weather resistance is lacking, therefore they are used for indoor applications only. At the same time, MBS gives translucent to crystal clear products, whereas with AIM, only translucent products are possible. In order to improve optical properties of AIM, it has to be reformulated. For transparent products, the core is made out of acrylic-styrene copolymers. Comparing silicone and all acrylic impact modifiers, PVC containing silicone-based products has superior low temperature impact properties. The incorporation of silicone into an acrylic impact modifier provides excellent weatherability, and thermal stability. It has shown improved retention of impact after outdoor weathering in PVC. ... 

Commercial copolymers. Styrene-butadiene block copolymer (SBS), acrylonitrile-butadiene-styrene (ABS), styrene-acrylonitrile (SAN), styrene-methylmethacrylate (SMMA), and styrene-maleic anhydride (SMA) are important styrene copolymers. 

Since A and B are constants for a given copolymer and the possible temperature interval is relatively limited, a transition is predicted at an approximately constant shear stress. Melt transitions have in fact been reported at approximately constant shear stresses for styrene-butadiene-styrene triblock copolymers (4). However, this behavior was certainly not observed for the styrene methylmethacrylate diblock copolymer,... 

MBA copolymer of butadiene, butylacrylate and methylmethacrylate Styrene-acrylonitrile copolymer (SAN)... 

Graft copolymer acrylonitrile-butadiene-styrene-methylmethacrylate, ABSM PDMS Ethylene-hydroxyethyl methacrylate (EHEMA)... 

S tyrene- acrylonitrile Styrene-butadiene elastomers Styrene-methylmethacrylate copolymer Sulfo-ethylene-propylene-diene monomer ionomers Syndiotactic polystyrene... 

Ki-aton G1600 SEES Perfluorinated ionomers Phenolic resins Polystyrene, head-to-head Poly(yinyl chloride), head-to-head S tyrene- acrylonitrile Styrene-butadiene elastomers Styrene-methylmethacrylate copolymer Sulfo-ethylene-propylene-diene monomer ionomers Vinylidene fluoride-hexafluoropropylene elastomers Chemigum... 

In addition to ABS, with polybutadiene as the elastifying component, there is another forerunner among the polymer products formulated for low-temperature impact resistance, PVC-U. Elastifying ligands include EVAC, EVAC/VC graft polymer, PAEA C (polyacrylic acid ester/vinyl chloride copolymer), ACE (acrylic ester/MMA graft polymer) as well as the chlorinated low-pressure polyethylene PE-C in use for over 35 years. All of the polymer blends listed here are suitable for outdoor applications since they contain no unsaturated components. Polybutadiene-modified products are better suited to interior applications, for example MBS, a methylmethacrylate/butadiene/styrene graft polymer [55]. 

Electron withdrawing substituents in anionic polymerizations enhance electron density at the double bonds or stabilize the carbanions by resonance. Anionic copolymerizations in many respects behave similarly to the cationic ones. For some comonomer pairs steric effects give rise to a tendency to alternate [378]. The reactivities of the monomers in copolymerizations and the compositions of the resultant copolymers are subject to solvent polarity and to the effects of the counterions. The two, just like in cationic polymerizations, cannot be considered independently from each other. This, again, is due to the tightness of the ion pairs and to the amount of solvation. Furthermore, only monomers that possess similar polarity can be copolymerized by anionic mechanism. Thus, for instance, styrene derivatives copolymerize with each other. Styrene, however, is unable to add to a methyl methacrylate anion [379-381], though it copolymerizes with butadiene and isoprene. In copolymerizations initiated by n-butyllithium in toluene and in tetrahydrofuran at —78°C, the following order of reactivity with methyl methacrylate anions was observed [382]. In toluene the order is diphenylmethyl methacrylate > benzyl methacrylate > methyl methacrylate > ethyl methacrylate > a-methylbenzyl methacrylate > isopropyl methacrylate > t-butyl methacrylate > trityl methacrylate > a,a -di-methylbenzyl methacrylate. In tetrahydrofuran the order changes to trityl methacrylate > benzyl methacrylate > methylmethacrylate > diphenylmethyl methacrylate > ethyl methacrylate > a-methylbenzyl methacrylate > isopropyl methacrylate > a,a -dimethylbenzyl methacrylate > t-butyl methacrylate. 

In 1983, Monsanto developed blends with co-continuous morphology, Triax 2000. These alloys comprised PC, ABS, and styrene-methylmethacrylate-maleic anhydride (SMMA-MA) (Jones and Mendelson 1985). One year later, PC was reactively blended with either ABS, SAN-GMA, or NBR or with graft copolymers of acrylonitrile-butadiene-a-methyl styrene-methyl-methacrylate (MeABS) and acrylonitrile-a-methyl styrene-methyl methacrylate copolymer (MeSAN) (Kress et al. 1986). The blends were commercialized by Bayer as Bayblend . 

PP has been blended with polyvinylchloride (PVC) for extrusion of pipes or electrical insulation [4]. The blends are compatibilized by addition of either methylmethacrylate-butadiene-st)TCne copolymer (MBS), a graft copolymer of acrylonitrile-butadiene-styrene-methylmethacrylate (ABSM), ethylene-vinylchloride copolymer (VCE), ethylene-vinyl-acetate-vinylchloride copol5oner (EVAc-VC), EVAc, etc. The blends also comprised other resin, viz. PE, PS or SBR, PMMA or PC, etc. 

Various workers have discussed aspects other than those mentioned above in studies of the viscoelastic properties of polymers. These include PVOH [62], hydroxy-terminated polybutadiene [63], styrene-butadiene and neoprene-type blends [64], and polyamidoimides [65]. Other aspects of viscoelasticity that have been studied include relaxation phenomena in PP [66] and methylmethacrylate-N-methyl glutarimide copolymers [67], shear flow of high-density polyethylene [68], Tg of PMMA and its copolymers with N-substituted maleimide [69] and ethylene-vinyl acetate copolymers [70], and creep behaviour of poly(p-phenylene terephthalate) [71] and PE [72]. 

Kalf et al. studied the effect of grafting cellulose acetate and methylmethacrylate as compatibilizers on acrylonitrile butadiene rubber (NBR) and styrene-butadiene rubber (SBR) blends. Morphology studies of the samples show an improvement in interfacial adhesion between the NBR and SBR phases in the presence of the prepared compatibilizing agents. The authors also reported the samples with grafted compatibilizers showed superior crosslink density and thermal stability, as compared to the blends without graft copolymers. ... 

This technique has been used extensively for the determination of functional groups, in polymers and copolymers (Chapter 3) and in comonomer analysis (Chapter 4). Both these aspects are concerned with the determination of polymer structure. For example the distinction between free and combined vinyl acetate in vinyl chloride - vinyl acetate copolymers (Section 3.4.4) or the elucidation of the structure of methylmethacrylate (MMA) - glycidyl methacrylate copolymers (Section 3.6.1) or the elucidation of the various types of unsaturation occurring in styrene - butadiene copolymers (Sections 3.9.3, 3.9.4). Typical infrared (IR) spectra of copolymers are shown in Figures 6.1 to 6.4. 

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